Inhibiting foaming of viscous petroleum oil



Patented July 11, 1944 INHIBITING FOAMING OF VISGOUS PETROLEUM OIL Carroll N. Kill, Jackson Heights, N. Y., assignor to Socony-Vacuum Oil Company, Incorporated, New York, N. Y., a corporation of New York No Drawing. Application February 19, 1941, Serial No. 379,645

3 Claims.

This invention has to do with the use of viscous oils such as gear oils, transmission oils, hydraulic oils and the like where the oil is used in an enclosed system and is subjected to vigorous agitation in use.

An oil of the type contemplated herein may be employed as a lubricant or it may serve the dual purpose of lubrication and power transmission, but irrespective of the purpose accomplished by these oils they have in common the feature of operating in enclosed systems, in most cases completely filled with oil, where any increase in volume due to foaming results in leakage and loss of product. Such a loss results in loss of lubrication and, in case of hydraulic oils, in decreased eiiiciency of power transmission Heretofore it has been the practice to produce gear oils and similar products which normally have a low or slight tendency to foam under conditions of use, by the selection of suitable petroleum stocks and refining methods to yield such a product. the final properties being largely dependent upon the selection of raw materials.

It is the primary object of this invention to provide a method to prevent the foaming of an oil of the class described which is normally susceptible to foaming under the conditions of vigorous agitation encountered in use by adding to the oil a minor proportion of an ingredient which will act as an anti-foaming agent. This invention also contemplates as a compositionof matter, the

viscous oil composition containing the antifoaming agent.

My invention is predicated upon the discovery that three organic thiophosphates, namely tricapryl monothiophosphate, triamyl-monothiophosphate and tri 2-ethyi-hexyl monothiophosphate are highly eflective as anti-foaming agents while many other organic compounds of phosphorus including some other thiophosphates had little or no effect in that regard. V

This unexpected property of the three thiophosphates contemplated herein is demonstrated by the test results set forth in Table I below where the foam retarding properties of thcse three thiophosphates are compared with the results obtained under similar test conditions with other organic compounds of phosphorus including other thiophosphates. The test employed in obtaining the data in Table I was an accelerated Table e Time for Per cent Oil Compound added 2% 3:3 foam after 85523 oil surface F. Minutes A None 100 L... Tricap l monothio- 1 100 None phos a A. Triam i monothlol 100 16 42 phosp etc. A. Trighenyl tetrathiol 100 100 150 p osphete. A 'Iriphenyl trithioi 100 98 150 phosphate.

A... Tri ole l monothiol 100 98 150 phosp ate. e A.. Tri beta phenyi ethyl 1 100 e150 thiophosphate. A... Difilletyl d thiopbosi 100 a 3..-. No 100 108 239 B 'Irlcap l monothiol 100 None phosp etc. 13.... Triamyl monothloi 100 None phosphate. 3.--- Tri-Z-ethyl-hexyl l 100 20 27 monothiophosphate. B. No 78 36 360 3.-.- Tricap l monothiol 78 2 phos ate. 3.... Trioleyl monotbio- 1 78 70 360 phosghate. B. Tribe phenyl ethyl l 78 88 300 thiophoaphate.

pin stirrer driven at 1750 R. P. M. for 20 minutes, after which the stirrer is removed from the oil and the'total volume of oil is observed and recorded. The volume percent of foam formed from 50 cc. of the original oil is a measure of the foaming tendency of the oil or oil blend. Readings were also made of the time required for the foam to subside so that a bulls eye of clear oil could be seen through the foam. Two diiferent oil stocks were used in the test. 011 A in the table below was a mineral gear oil having a Saybolt vis cosity of 05 seconds at 210 F. and oil B was mineral gear oil having a Saybolt viscosity of 250 seconds at 210 F.

From the foregoing test results it will be seen that thiophosphates from the group consisting of trlcapryl monothiophosphate. triamyl monothiophosphate and tri-2-ethvl-hexyl monothiophosservice test simulating the actual. working condltions of transmission and hydraulic oils. In this test a 50 cc. sample of-oil is placed in a 1.5 in. 1.1). graduate and violently agitated with e. hairphate are effective to materially reduce, and in some instances to entirely eliminate, the foaming tendency oi! the oil while the other phosphates and thiophcsphates temed actually increased the foaming tendency.

The monothiophosphates contemplated herein as anti-foaming agents may be used in the oil in amounts ranging from about 0.1 percent to about 5.0 percent.

' I claim: 7

1. In the method of utilizing a viscous petroleum oil in a system wherein the oil is subjected to vigorous agitation and normally tends to develop a substantial quantity of foam, the step of inhibiting the foaming of the oil by incorporati'ng therein a minor proportion, from about 0.1 percent to about 5.0 percent, of a. thiophosphate selected from the group consisting of trl-capryl monothiophosphate, and tri-2-ethyl-hexyl-monothiophosphate.

2. In the method of utilizing a. viscous petroleum oil in a system wherein the oil is subjected to vigorous agitation and normally tends to develop a. substantial quantit of foam, the step of inhibiting the foaming of the oil by incorporating therein a minor proportion, from about 0.1 percent to about 5.0 percent of tri-capryl-monot-hiophosphate.

3. In the 'method of utilizinga viscouspetroleum oil ina system wherein the oil is subjected to vigorous agitation and normally tends to develop a substantial quantity of foam, the

7 step of inhibiting the foaming of the oil by incorporating therein a minor proportion from about 0.1 percent to about 5.0 percent of tri-Z-ethylhexyl monothiophosphate.

CARROLL N. RILL. 

